Early technology for vascular access required surgical opening of the skin, viewing of the vessel to be catheterized, and placement, under sterile procedure of a stainless steel needle. After the insertion process, the skin was approximated and the access site covered to prevent infection. The process required a competent physician, and was indicated only in rare instances when the patient required IV sustenance or required replacement fluids in association with major surgery.
Improved technologies followed wherein the vessel was accessed by insertion of a stainless steel needle directly through the skin into the vessel. The insertion needle was left in place, covered by a protective cover, and taped in place to prevent dislodging or movement. Should significant movement of the rigid needle take place, the vessel could be punctured from the inside causing a hematoma to form in the surrounding tissue with associated pain and discomfort to the patient. While this technique was much simpler than surgical placement of the needle, it still required significant skill for correct needle insertion, and substantial restriction of patient movement to prevent complications from the stainless steel needle damaging the vessel or becoming displaced from the vessel.
More recent technologies are represented by devices with a tough, flexible plastic catheter positioned coaxially over a stainless steel guide needle. The stainless steel guide needle is inserted through the patient's skin to puncture one wall of the targeted vessel far enough for the catheter to also penetrate the vessel wall. The guide needle is then withdrawn, leaving only the plastic catheter in the vessel. The relatively flexible catheter can then be carefully slid further into the vessel without causing vessel damage or additional pain to the patient. This technology represented a significant improvement over prior techniques for long term vascular access and improved comfort to the patient. However, for catheterizations that involve relatively high rates of fluid transfer, relatively large bore catheters are required. For patients having small or “hard to find” vessels the caregiver must exercise significant skill and care to successfully introduce the relatively large bore guide needle into a vein. Failed insertions can be common is such circumstances. Partial puncture into the side of the vessel or a complete miss of the targeted vessel can require a one or more additional attempts, causing pain and suffering for the patient, and substantial anxiety for the caregiver.
To simplify procedures and reduce the stress associated with intra-vascular catheterization, many catheter devices have been conceived. For example, in U.S. Pat. No. 4,588,398, to Daugherty et al., designed a particular geometry for the leading edge of the catheter to minimize the force needed to penetrate the skin and vessel wall as the guide needle punctures each layer. Catheter materials and surface coatings were further defined to minimize catheter wall thickness and reduce friction as the catheter is inserted and the guide needle retracted. While the materials cited have provided improved comfort in intra-vascular catheters, the guide needle has continued to be a major source of pain and complications for catheterization procedures.
In other improvements, guide needle tip geometry has been developed to reduce the puncture force required to insert the guide needle through the skin and penetrate the vessel wall. Suzuki defined a tip geometry, in U.S. Pat. No. 4,565,545, that incorporates a tapered outside diameter in the needle tip as well as beveled tip angles that reduce puncture force and reduce hematosis resulting from the smaller lumen created in the blood vessel wall. In U.S. Pat. No. 5,618,272, Nomura described a guide needle in which the outer diameter of the needle is reduced immediately after the beveled distal end of the needle. The distal end of the catheter is positioned at this reduced diameter section of the needle so that the catheter insertion requires very little additional force to fully penetrate the vessel. This reportedly results in almost no additional pain once the needle has been inserted. Both of these guide needle designs rely on a relatively large bore needle diameter as required by the inner diameter of the catheter needed for the procedure. So the problems of initial pain at the time of skin and vessel puncture, as well as the difficulty of finding and successfully penetrating the targeted vessel remain as key sources of anxiety for the patient and the caregiver.
Suzuki, et al., (U.S. Pat. No. 4,629,450) improved the catheter design for certain catheterization operations by including a dilator element between a relatively small diameter guide needle and the catheter. Upon removal of the guide needle, a guide wire is inserted through the dilator into the vessel, wherein it is positioned inside the blood vessel or further advanced to within a body organ. The catheter is subsequently inserted over the dilator, through the lumen in the vessel, and over the guide wire to direct its desired position. The use of a relatively small diameter guide needle allows for less painful puncturing of the skin and vessel, while the dilator expands the puncture to facilitate introduction of a larger bore catheter. Although this design may be suited for procedures requiring insertion of a guide wire, the geometry of the dilator and its insertion technique make it difficult to position a fluid intra-vascular catheter in the vessel without blood leakage since the means of advancing the needle, advancing the dilator, retracting the needle, further advancing the dilator, advancing the catheter, and then finally retracting the dilator is time consuming, can introduce pathogens or allow blood to escape, and requires extensive technician training.
With many of the described catheterization technologies, blood contamination is risked when an intra-vascular catheter is inserted. Blood flashback can escape the catheter hub when the guide needle is removed and before the intra-vascular solution tubing can be connected, thus exposing the caregiver and patient to blood leakage. Several notable valve designs have been patented to reduce this blood leakage. For example, in U.S. Pat. No. 4,387,879, Tauschinski describes a self sealing elastomeric disc that can be incorporated into a connector body to interface with a parenteral supply solution and an intra-vascular catheter. Similarly, Motisi et al, describe a one way valve in the body of a catheter apparatus in U.S. Pat. No. 5,843,046. However, the necessity of a plunger and introduction of needle or tubing through the plunger decreases the inside diameter of the catheter and reduces the fluid flow rates for this design. An “O” ring in the valve can prevent leakage from around the plunger, but this decreases the inside diameter of the large bore catheter. The valve is held in place by a “cap” which puts its placement deeper into the throughbore, out of reach of conventional intra-vascular tubing or conventional syringes. The “cap” also prevents connection to conventional tubing or conventional syringes. This valve is bulky and decreases the size of the intra-vascular catheter. It also cannot be opened by conventional devices used by those skilled in the art.
In light of the problems remaining in the art, it would be beneficial to have relatively simple catheter insertion devices that minimize possibilities of blood contamination or escape. It would be desirable to have comfortable catheters that minimize the possibility of causing a hematoma. The present invention provides these and other features that will be apparent upon review of the following.